Science 9
Unit 1: Atoms, Elements, and Compounds
Name: __________________
M. Harvey 2013
Date: ____________
3.2 – Names and Formulas of Ionic Compounds notes
What patterns do you notice for the following ionic compound names?
lithium fluoride
calcium chloride
copper oxide
zinc bromide
o All ionic compounds are composed of positive ions and negative ions.
o Ionic compounds have chemical names (ex: sodium chloride), and chemical
formulas (ex: NaCl).
Chemical name
o The name indicates which elements are parts of the compound.
o International Union of Pure and Applied Chemistry (IUPAC) are responsible
for the rules for naming compounds.
 The first part of the name is the positive ion which is ALWAYS a
metal. Example: sodium chloride
 The second part of the name is the negative ion with is ALWAYS a
non-metal. Example: sodium chloride
 The non-metal ion’s name always ends with the suffix “ide”. For
example chlorine
chloride (sodium chloride).
Science 9
Unit 1: Atoms, Elements, and Compounds
Name: __________________
M. Harvey 2013
Date: ____________
o Rules for writing the names of ionic compounds:
1. Identify the metal ion.
2. Identify the non-metal ion. Change the ending to “ide”.
3. Write the name of the compound.
Examples:
Elements forming ionic compounds
Name of ionic compound
calcium + nitrogen
calcium nitride
potassium + oxygen
lithium + chlorine
silver fluoride
AlI3
Na2O
RbF
Sr3P2
Chemical formula
o The chemical formula contains chemical symbols to identify the each ion in
the ionic compound (example: AgI -> silver iodide)
o The chemical formula also shows the number of ions in each compound
(example: K2S-> potassium sulphide).
Science 9
Unit 1: Atoms, Elements, and Compounds
Name: __________________
M. Harvey 2013
Date: ____________
o Rules for writing the chemical formulas of ionic compounds:
1. Identify each ion and its charge.
2. Determine the total charges needed to balance positive with negative.
3. Note the ratio of positive ions to negative ions/swap charges.
4. Use subscripts to write the formula. *don’t need to write 1
Li
Elements forming ionic compounds
Chemical formula of ionic
compound
Li+ with Cl-
LiCl
Li+
Cl
Cl-
LiCl
Ca2+ with FCa2+
F-
CaF2
Na+ with S2-
Ca2+ with S2-
zinc oxide
barium phosphide
Science 9
Unit 1: Atoms, Elements, and Compounds
Name: __________________
M. Harvey 2013
Date: ____________
Multivalent metal
o “multi” = many “valent” = capacity to bond
o Multivalent metals can form two or more different positive ions with
different ion charges (example: Iron -> 3+ and 2+).
o The periodic table always list the most common ion charge first.
o What is the most common ion charge for Iron? Fe3+ or Fe2+
o To distinguish between the different ions formed, Roman Numerals are used.
o Rules for writing the chemical formula for multivalent metals:
1. Identify each ion and its charge.
2. Determine the total charges needed to balance positive with negative.
3. Note the ratio of positive ions to negative ions.
4. Use subscripts to write the formula. *1 is not written
Elements forming ionic compounds
Chemical formula of ionic
compound
chromium (II) chloride
chromium (II): Cr2+
chloride: ClCl
Cr
Cl
chromium (III) chloride
copper (I) sulphide
CrCl2
Science 9
Unit 1: Atoms, Elements, and Compounds
Name: __________________
M. Harvey 2013
Date: ____________
iron (II) phosphide
iron (III) phosphide
o Rules for writing the chemical name for multivalent metals:
1. Identify the metal
2. Verify that it can form more than one kind of ion by checking the
periodic table.
3. Determine the ratio of the ions in the formula.
4. Note the charge of the negative ion from the periodic table.
5. The positive and negative charges must balance out. Determine what
the charge needs to be on the metal ion to balance the negative ion.
6. Write the name of the compound.
Chemical formula
Chromium: Cr
Bromine: Br-
3+
Name of multivalent ionic
compound
CrBr2
2+
or Cr
chromium (II) bromide
FeI2
Science 9
Unit 1: Atoms, Elements, and Compounds
Name: __________________
M. Harvey 2013
Date: ____________
PbF2
MnO
Fe2O3
Polyatomic Ions
o Rules for writing the chemical formula for polyatomic ions:
1. Identify each ion and its charge.
2. Determine the total charged needed to balance positive with negative.
3. Note the ratio of positive ions to negative ions.
4. Use subscripts and brackets to write the formula.
Chemical formula
NaCH3COO
Cr(OH)3
(NH4)3PO4
Name of polyatomic ion
Science 9
Unit 1: Atoms, Elements, and Compounds
Name: __________________
Chemical name
M. Harvey 2013
Date: ____________
Chemical formula of
polyatomic ion
sodium chromate
lithium dichromate
magnesium hydroxide
pg. 92 in textbook